Abstract: Herein polymers and particles which comprise a plurality of dihydropyridazine or hydropyridazine functional groups are described. Methods for their formation and specific monomers which may be used in their formation are also described. The polymers and particles are UV absorbing, hydrogen-donor antioxidant materials which signal a depletion of antioxidant ability by a decrease in visible fluorescence. These polymers and particles may be used as UV protectants for a variety of materials and substrates and may even be used in a topically applied formulation for human skin.